Effects of chronic ethanol ingestion on male and female rat liver glycogen phosphorylase phosphatase

Alcohol-induced suppression of gluconeogenesis is greater in ethanol fed female rat hepatocytes than males

The impact of alcohol-induced suppression on hepatic gluconeogenesis (HGN) after chronic ethanol consumption between males and females is unknown. To determine the effects of chronic alcohol consumption (8 weeks) on HGN, the isolated hepatocyte technique was used on 24 h fasted male and female Wistar rats. Livers were initially perfused with collagenase and the hepatocytes were isolated. Aliquots of the cell suspension were placed in Krebs-Henseleit buffer and incubated for 30 min with lactate, [U -14C]lactate, and nine different concentrations of ethanol (EtOH). Dose-effect curves were generated for the determination of maximal and half-maximal alcohol-induced inhibition on HGN. There was no significant difference in HGN (lactate only and no EtOH) between males and females fed the control diet (88.5 +/- 5.1 nmol/mg protein/30 min). Similarly, the HGN (lactate only and no EtOH) in males fed the ethanol diet (ME) were not significantly different (82.8 +/- 3.5 nmol/mg protein/30 min) compared to controls. In contrast, the females chronically fed the ethanol diet (FE) had significantly (P < .05) lower HGN (67.8 +/- 4.6 nmol/mg protein/30 min) compared to both ME and controls. With alcohol in the incubation medium, the HGN significantly (P<.05) declined in all groups. While alcohol suppressed HGN to a larger (P < .05) extent in ME (45.8 +/- 3.7 nmol/mg protein/30 min) compared to controls (64.0 +/- 3.8 nmol/mg protein/30 min), the inhibition was even greater (P < .05) in FE (32.7 +/- 3.2 nmol/mg protein/30 min). The more pronounced effect of chronic alcohol consumption on HGN in the presence of ethanol in female hepatocytes was supported by the concomitant decreases (P < .05) in 14C-lactate incorporation into 14C-glucose, lactate uptake, and 14C-lactate uptake. The results suggest that chronic alcohol consumption elicits a greater reduction on HGN in the presence of ethanol in the hepatocytes of females compared to males.

Chronic ethanol consumption and liver glycogen synthesis

Chronic ethanol consumption results in a dramatic decrease in liver glycogen concentrations, which could be related to either a depressed rate of synthesis or an increased rate of breakdown. Earlier studies suggested that there is not an increase in the rate of glycogenolysis as glycogen phosphorylase activities are not elevated. In the present study it was observed that the incorporation of radiolabeled glucose into glycogen was significantly depressed in hepatocytes from ethanol-fed rats under both anaerobic and aerobic conditions. Chronic ethanol consumption decreased the total glycogen synthase (a + b) activity, which correlated closely with a loss in glycogen synthase protein. However, glycogen synthase messenger RNA levels were not depressed, which indicated posttranscriptional modifications affecting both activity and protein levels. The concentration of glucose transporter 1 was also decreased due to ethanol consumption, but glucose transporter 2 levels were not altered. This latter result suggests that glucose transport in the perivenous region of the liver lobule may be decreased in chronic ethanol consumers. The alterations in glucose transport protein and glycogen synthesis observed in this study may contribute to lowered glycogen synthesis, but do not appear to account for the magnitude of the decreases in glycogen levels and rate of synthesis. Indeed, ethanol effects on glycogen metabolism are likely to be exerted at several levels, including posttranslational modulation of enzyme activities.

The effect of myo-inositol on ethanol-induced metabolic changes and insulin concentration in the rat

Myo-inositol was found to possess several beneficial effects on the organism. The effect of myo-inositol on ethanol-induced metabolic changes and insulin concentration was investigated in growing rats. The increase in liver triglycerides induced by ethanol drinking (10% ethanol solution as the only drinking fluid for 10 days) was completely abolished by simultaneous treatment with myo-inositol (0. 1 g/100 g b.w., every day given intragastrically). The ethanol-evoked decrease in blood insulin and the increase in liver glycogen were also partially prevented by myo-inositol. Myo-inositol did not cause any undesirable metabolic changes in the rats. The results indicate that myo-inositol may be useful in the treatment of some metabolic consequences of alcohol drinking.

Impaired glucose homeostasis during postimplantation pregnancy in the mouse following acute exposure to ethanol, with particular reference to the uterus and embryo

Dramatic changes in the levels of plasma glucose and lactate and liver glycogen were observed in mice, given an intraperitoneal injection of ethanol (3.5 g/kg body weight) on Day 9 of pregnancy, during the period of time (6 h) required to clear the drug from the circulatory system. These alterations were accompanied by significant changes in the rates of accumulation of some glycolytic and citric acid cycle intermediates in the uterus, including glucose-6-phosphate, fructose-6-phosphate, lactate, citrate, alpha-ketoglutarate, and succinate. Although the changes in some metabolic parameters were very transient, not all metabolites returned to control values by the time that the drug had been cleared from the maternal system. Alcohol also impaired the capacity of Day 9 mouse embryos to metabolize [14C]glucose under culture conditions in vitro and significantly increased the amount of the aldohexose accumulating in the fetal membrane fluid when administered on Day 14 of pregnancy. However, ethanol neither influenced the ratio of NADH to NAD+ in the uterus nor changed the glycolytic and respiratory activity of the uterine endometrium when coincubated with the tissue in vitro. The results indicate that glucose homeostasis is impaired in both the embryo and the maternal system of mice acutely exposed to alcohol during the teratogenically sensitive period of postimplantation pregnancy and support the thesis that this phenomenon may present an important mechanism underlying the embryo-toxic effects of alcohol consumed under "binge" drinking conditions during pregnancy. However, the results also suggest that the effects registered at the uterine level most likely involve stress reactions and acetate rather than primary actions of the drug on the organ.

Metabolic response to starvation at late gestation in chronically ethanol-treated and pair-fed undernourished rats

To study the role of undernourishment in the negative effects of ethanol during pregnancy and to determine whether maternal ethanol intake modifies metabolic response to starvation at late gestation, female rats receiving ethanol in their drinking water before and during pregnancy (ethanol group) were compared with animals that received the same amount of solid diet as the ethanol group rats (pair-fed group) and with normal rats fed ad libitum (control group). All animals were killed on the 21st day of gestation, either in the fed state or after 24-hours fasting. The body weight of ethanol rats was lower than that of controls but higher than that of pair-fed rats. When compared with controls, ethanol and pair-fed rats had reduced fetal body weights, whereas fetal body length was reduced only in the former. In the fed state, blood glucose concentration was lower in the ethanol and pair-fed rats and fetuses than in controls. Twenty-four-hour starvation caused a reduction in this parameter only in control and ethanol mothers. In the fed state, maternal liver glycogen concentration was lower in ethanol and higher in pair-fed mothers than in controls. Blood beta-hydroxybutyrate levels were higher in ethanol-treated mothers than in the others, and 24-hour starvation increased this parameter in ethanol and control rats to a greater extent than in the pair-fed ones. Liver triacylglyceride concentration was higher in ethanol-treated mothers than in the other two groups, and starvation caused this concentration to increase in ethanol and control groups but not in the pair-fed group.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycolysis in the mouse uterus during the early post-implantation stages of pregnancy and the effects of acute doses of ethanol

The objective of this study was to assess the possibility that, in mice, alcohol interferes with uterine glycolysis to influence indirectly embryonal development. Glycolysis was found to be a major metabolic process in the mouse uterus and its pattern of activity changed during post-implantation pregnancy between days 5 and 9. This was evidenced by changes in glycolytic enzymes and intermediates, and in the capacity of endometrial preparations to consume oxygen and produce lactate during incubation in vitro. The intraperitoneal administration of ethanol at 3.0 and 6.0 gm/kg body weight, but not at 1.5 gm/kg body weight, on day 9 of pregnancy modified glycolysis in the uterus after 2 hours, resulting in significant changes in the rates of accumulation of glucose, glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-diphosphate, and citrate. These effects were not mediated by changes in redox state, since the ratio of lactate to pyruvate remained unchanged after injection of ethanol. Citrate was considered to be a major factor involved both in the regulation of uterine glycolysis and in the ethanol-induced alterations in the levels of hexose phosphates. The elevated levels of uterine glucose registered after treatment with ethanol were related to an acceleration of glycogen degradation in the liver and not in the uterine endometrium. The results suggest that part of the adverse action that these doses of ethanol exert on embryonal development stems from indirect effects that involve uterine functions relating to the nurture of the conceptus via glycolysis.